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Article

Successive Activation of C–H and C–O Bonds of Vinyl Ethers by a Diphosphine and Hydrido-Bridged Diiridium Complex

by
Yoshinori Takahashi
,
Takuya Shimbayashi
and
Ken-ichi Fujita
*
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
*
Author to whom correspondence should be addressed.
Inorganics 2019, 7(10), 121; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics7100121
Submission received: 21 August 2019 / Revised: 20 September 2019 / Accepted: 20 September 2019 / Published: 3 October 2019
(This article belongs to the Special Issue Iridium Complexes)
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Abstract

:
The reaction of [(Cp*Ir)2(μ-dmpm)(μ-H)][OTf] (2) [Cp* = η5-C5Me5, dmpm = bis(dimethylphosphino)methane] with 2,3-dihydrofuran gives [(Cp*IrH)2(μ-dmpm){μ-(2,3-dihydrofuranyl)}][OTf] (3) in an isolated yield of 70% via the C–H bond activation at the 5-position of 2,3-dihydrofuran. Complex 3 is slowly converted into [(Cp*Ir)2(μ-dmpm)(μ-C=C(H)CH2CH2OH)][OTf] (4) quantitatively via the proton-mediated C–O bond activation. The reaction of 2 with ethyl vinyl ether gives [(Cp*Ir)2(μ-dmpm)(μ-CH=CH2)][OTf] (5) in the isolated yield of 64% via the successive activation of C–H and C–O bonds.

Graphical Abstract

1. Introduction

Vinyl ethers are versatile substrates used to synthesize various oxygen-containing organic compounds, such as functionalized alkenes or ketones [1,2,3,4,5]. Many transition metal-catalyzed synthetic reactions using vinyl ethers as starting materials, such as the Heck-type reaction [6,7,8,9], hydrofunctionalization [10,11,12,13], cycloaddition [14,15,16], Claisen rearrangement [17,18,19], alcoholysis [20,21], and polymerization [22,23,24] have been known. Further reactions involving the C–H [25,26,27,28] or C–O [29,30] bond activation of vinyl ethers as a key step have been reported. These synthetic methods are powerful because there is no need for the pre-functionalization of substrates and specificity in their skeletal rearrangement. To obtain insight into the reaction mechanism and reactivity to develop better catalytic reactions, it must be important to reveal the fundamental aspects of the activation of vinyl ethers by transition metal complexes. However, although there are many studies on C–H [31,32,33,34,35] and C–O [36,37,38,39,40,41] bond activation reactions by transition metal complexes, fundamental studies on the C–H and C–O bond activation of vinyl ethers by transition metal complexes are relatively unexplored [42,43,44,45,46,47,48,49,50,51,52,53].
Meanwhile, much attention has been paid to the activation of organic molecules by multinuclear complexes in expectation of the synergetic effect of the multi-metal centers. Therefore, various multimetallic systems that are capable of the bond activation of organic substrates were disclosed [54,55,56,57,58]. We have reported the facile activation of the sp2 C–H bonds of aromatic compounds and an olefin by a diphosphine and hydrido-bridged diiridium complex, [(Cp*Ir)2(μ-dmpm)(μ-H)2]2+ (1) [Cp* = η5-C5Me5, dmpm = bis(dimethylphosphino)methane], in which the cationic 32e− IrII–IrII complex, [(Cp*Ir)2(μ-dmpm)(μ-H)]+ (2), would be a true active species [59,60,61]. In the course of our study on the chemistry of 2, we have found that the reaction of 2 with vinyl ethers resulted in the activation of the vinylic C–H bond followed by the activation of the sp2 C–O bond. In this paper, we report the successive activation of C–H and C–O bonds of 2,3-dihydrofuran and ethyl vinyl ether by 2, which affords μ-vinylidene and μ-vinyl complexes.

2. Results and Discussion

2.1. C–H Activation of 2,3-Dihydrofuran

As we previously reported, the treatment of 1 with methyl triflate at −30 °C followed by warming to room temperature afforded the 32e− complex 2 as a purple powder, which is highly active for C–H activation [60]. The addition of 2,3-dihydrofuran to the preformed 2 followed by stirring at 0 °C for 18 h gave complex 3 in an isolated yield of 70% via selective C–H activation at the 5-position and iridation at the 4-position (Equation (1)). We have already reported the regioselective C−H activation of furan at the 2-position by the reaction with preformed 2, giving stable product without C–O bond activation [59]. In the 1H NMR spectrum of 3, two doublets due to hydrides were observed at δ −16.27 (JPH = 32 Hz) and −18.23 (JPH = 42 Hz), which indicated that these hydrides coordinated to each iridium center with terminal fashion. In the 13C{1H} NMR, a signal due to C5 was observed at a lower field (δ 220.4), which indicated its carbene character. On the other hand, a signal due to C4 was observed at a relatively high field (δ 47.4). By considering these signal patterns, the structure of 3 can be described as oxacarbene (I) rather than μ-vinyl (II) [62], which would be simply formed via the C–H activation at the right iridium center followed by the coordination of C=C moiety to the left iridium center (Figure 1). The structure of 3 was confirmed by X-ray diffraction study (details are indicated in the Supplementary Materials). The molecular geometry of 3 is shown in Figure 2. The length of the Ir(1)–C(26) bond [1.978(11) Å] is slightly longer than that of typical iridium-carbon double bond [63,64] but it is considerably shorter than that of the iridium-alkenyl carbon single bond [65,66]. The distance between Ir(2) and C(26) [2.875(12) Å] indicates that there is no bonding interaction. Therefore, the solid state structure of 3 can be described as the oxacarbene (I).
Inorganics 07 00121 i001

2.2. C–O Bond Activation of 3

In a dichloromethane solution, complex 3 was slowly converted to a μ-vinylidene complex 4, which was formed by the activation of the C–O bond (Equation (2)). After the reaction at room temperature for 150 h, the quantitative formation of 4 was observed. In the 1H NMR spectrum of 4, a signal due to the bridging hydride was observed at δ −17.97 as a triplet (JPH = 11 Hz), and a signal due to the vinylic proton was observed at δ 5.21. In the 13C{1H} NMR spectrum, the signals due to the α- and β-carbon of the vinylidene moiety were observed at δ 192.5 and 121.8, respectively. These signal patterns are very similar to those of the vinylidene-bridged diiridium complexes, which have been previously reported by Cowie et al. [67,68]. The structure of 4 was unequivocally confirmed by X-ray diffraction study (Figure 3, details are indicated in the Supplementary Materials).
Inorganics 07 00121 i002
The proton-mediated ring opening reaction of a [5-(2,3-dihydrofuranyl)]ruthenium complex has been reported by Gunnoe [48]. Thus, we next examined the effect of Brønsted acid and base towards the conversion of 3 into 4. When the solution of 3 in dichloromethane containing acetic acid (0.9 equiv.) was stirred at room temperature, complete conversion into 4 was observed after 75 h, while the reaction in the absence of the acid required 150 h (vide supra). The employment of stronger acid resulted in the formation of unidentified byproduct, probably by the unexpected decomposition of the intermediate. On the other hand, the addition of a base (2,2,6,6-tetramethylpiperidine) suppressed the conversion into 4 (similar reaction of 3 in the presence of 2,2,6,6-tetramethylpiperidine (1.8 equiv.) resulted in the formation of 4 in ca. 10% yield after 100 h). The employment of other base gave rise to the formation of other byproduct, probably formed by the ligation to the iridium centers. These results obviously suggest that the C–O bond cleavage is proton-mediated. A plausible pathway for the transformation of 3 into 4 is as follows (Scheme 1): First, protonation at the oxygen atom in 3 affords A or B. Then, the C–O bond cleavage and elimination of one of the iridium hydrides as a proton occurs to give product 4. It should be noted that this pathway corresponds to the reverse reaction of intramolecular hydroalkoxylation of 3-butyne-1-ols to produce 2,3-dihydrofurans [69].

2.3. Successive Activation of C–H and C–O Bonds of Ethyl Vinyl Ether

We next studied the reactivity of 2 with acyclic vinyl ether. The reaction of the preformed 2 with ethyl vinyl ether at 0 °C for 20 h gave a μ-vinyl complex 5 in an isolated yield of 64% with a concomitant formation of ethanol (Equation (3)) (similar reactions of 2 with n-butyl vinyl ether and isopropyl vinyl ether gave the same μ-vinyl complex 5 accompanied by the release of 1-butanol and 2-propanol, respectively). In the 1H NMR spectrum of 5, the two signals due to Cp* ligands were non-equivalently observed at δ 1.93 and 1.78 and three signals due to μ-vinyl protons were observed at δ 7.62, 3.82, and 2.02. No signals for hydrides were observed. In the 13C{1H} NMR spectrum, the signals due to the μ-vinyl carbons were observed at δ 113.2 (Cα) and 45.6 (Cβ). All the NMR data of 5 were consistent with the proposed structure, and the signal patterns were similar to the related dicationic μ-vinyl complex [(Cp*Ir)2(μ-dmpm)(μ-CH=CH2)(μ-H)][OTf]2, which was previously reported by us [70]. In addition, the structure of 5 was confirmed by X-ray diffraction study (Figure 4, details are indicated in the Supplementary Materials).
Inorganics 07 00121 i003
To obtain information concerning the mechanism of the formation of 5, the reaction of 2 with ethyl vinyl ether was monitored by the 1H and 31P{1H} NMR analyses from −40 °C to room temperature. At the early stage of the reaction (45 min at −40 °C, 75% conversion of 2), the formation of an intermediate C (Figure 5, ca. 30% yield) was observed, which was afforded by the C–H activation of terminal vinyl moiety in ethyl vinyl ether. In addition to C, the formation of other two species, those might be intermediates in the transformation of C to 5, was observed during the NMR monitoring. However, we could not determine their structures so far. The observed 1H and 31P{1H} NMR signals for C are as follows: In the 1H NMR spectrum, two signals due to hydrides were observed at δ −16.76 (terminal) and at δ −26.05 (bridge), which is a typical signal pattern for the C–H activation product formed from 2 [60]. The signals due to two vinylic protons were observed at δ 6.72 and 5.74. These signals were mutually coupled (JHH = 6 Hz), indicating cis configuration of the alkenyl moiety. The signals for ethoxy group were found at δ 3.68 and 1.23. In the 31P{1H} NMR spectrum, two signals were observed at δ −34.8 and −42.9 as doublets coupling to each other (JPP = 52 Hz). Upon warming the sample to room temperature, the intermediate C disappeared, and 5 was formed quantitatively accompanied by the release of ethanol. Although the detailed mechanism for the C–O activation (C to 5) is currently not clear, we believe that this is also a proton-mediated process, similar to the formation of 3.

3. Materials and Methods

3.1. General

All manipulations were performed under a dry argon atmosphere with standard Schlenk techniques. 1H NMR spectra were measured with JEOL EX-270 and JEOL A-500 spectrometers (JEOL Ltd., Tokyo, Japan). Elemental analyses were carried out at the Microanalysis Center of Kyoto University. The complex 1 was prepared according to the literature [60]. Solvents were dried by using standard procedures and distilled prior to use. Other reagents were used as obtained from commercial sources.

3.2. C–H Bond Activation of 2,3-dihydrofuran to Give 3

A two-necked 30 mL flask was charged with 1 (238 mg, 0.299 mmol) and dichloromethane (6 mL) at −30 °C. Methyl triflate (49.1 mg, 0.299 mmol) was added to the solution and the reaction mixture was stirred for 2 h. After the removal of the solvent in vacuo at −30 °C, the flask was warmed to room temperature. The brown solid was turned into purple. To the purple solid, 2,3-dihydrofuran (6 mL) was added at −30 °C and stirred for 18 h at 0 °C. After the removal of the solvent in vacuo, the washing of the residue with toluene and hexane gave the light yellow powder of 3 (213 mg, 70%). 1H NMR (500 MHz, CD2Cl2): δ 4.23 (1H, d, J = 5 Hz, C=CH–), 4.04−3.88 (2H, m, O–CH2–CH2), 2.49 (1H, m, CH–CHH–CH2), 1.91 (15H, d, J = 3 Hz, Cp*), 1.87 (15H, s, Cp*), 1.76 (3H, d, J = 10 Hz, PMe), 1.66 (d, J = 9 Hz, PMe and overlapped CH–CHH–CH2), 1.65 (3H, d, J = 10 Hz, PMe), 1.53 (3H, d, J = 10 Hz, PMe), −16.27 (1H, d, J = 32 Hz, Ir–H), −18.23 (1H, d, J = 42 Hz, Ir–H). 13C{1H} NMR(125.65 MHz, CD2Cl2): δ 220.4 (m, Ir–C), 121.4 (q, J = 322 Hz, CF3), 95.7 (d, J = 2 Hz, C5Me5), 95.0 (d, J = 2 Hz, C5Me5), 75.5 (s, O–CH2–CH2), 47.4 (s, C=CH), 39.1 (s, CH–CHH–CH2), 26.6 (dd, J = 43 Hz, 35 Hz, P–CH2–P), 22.8 (dd, J = 39 Hz, 5 Hz, PMe), 22.1 (d, J = 32 Hz, PMe), 21.8 (dd, J = 35 Hz, 5 Hz, PMe), 17.2 (d, J = 33 Hz, PMe), 10.7 (s, C5Me5), 10.2 (s, C5Me5). 31P{1H} NMR (109.25 MHz, CD2Cl2): δ −33.2 (d, J = 8 Hz), −41.7 (d, J = 8 Hz). Anal calcd for C30H51F3Ir2O4P2S: C, 35.63; H, 5.08. Found: C, 35.35; H, 5.01.

3.3. Conversion of 3 into Vinylidene Complex 4

In a NMR tube, 3 (21.8 mg, 0.0216 mmol) and CD2Cl2 (0.6 mL) were placed. The progress of the reaction was monitored by 1H NMR analysis. Quantitative conversion of 3 into the μ-vinylidene complex 4 was observed after 150 h. Samples for the elemental analysis were obtained by the slow diffusion of hexane into a dichloromethane solution of 4. 1H NMR (500 MHz, CD2Cl2): δ 5.21 (1H, m, C=CH), 3.69–3.57 (2H, m, CH2–CH2–OH), 2.67 (m, 1H, =CH–CHH–CH2), 2.39 (m, 1H, =CH–CHH–CH2), 2.02 (15H, s, Cp*), 1.91 (15H, s, Cp*), 1.63–1.56 (9H, m, 3 PMe), 1.48 (3H, d, J = 8 Hz, PMe), −17.97 (1H, t, J = 11 Hz, Ir–H–Ir). 13C{1H} NMR(125.65 MHz, CD2Cl2): δ 192.5 (t, J = 9 Hz, Ir–C–Ir), 121.8 (s, C=CH), 121.3 (q, J = 322 Hz, CF3), 96.5 (d, J = 2 Hz, C5Me5), 95.9 (d, J = 2 Hz, C5Me5), 63.9 (s, CH2–CH2–OH), 39.0 (s, CH–CH2–CH2), 23.1 (t, J = 37 Hz, P–CH2–P), 20.1–19.6 (m, two PMe carbons), 15.6 (dd, J = 32 Hz, 15 Hz, PMe), 13.0 (dd, J = 35 Hz, 13 Hz, PMe), 11.1 (s, C5Me5), 10.4 (s, C5Me5). 31P{1H} NMR (109.25 MHz, CD2Cl2): δ −14.84, −14.86. Anal calcd for C30H51F3Ir2O4P2S: C, 35.63; H, 5.08. Found: C, 35.58; H, 4.97.

3.4. Reaction of Complex 1 with Ethyl Vinyl Ether to Give 5

After the treatment of complex 1 (202 mg, 0.255 mmol) with MeOTf (41.8 mg, 0.255 mmol) similar to the procedure described above (Section 3.2), ethyl vinyl ether (5 mL) and dichloromethane (2.5 mL) were added to the purple residue. The solution was stirred at 0 °C for 20 h then volatiles were removed in vacuo. The residue was washed with toluene to give the orange powder of 5 (157 mg, 64%). 1H NMR (500 MHz, CD2Cl2): δ 7.62 (1H, m, Ir–CH=), 3.82 (1H, m, –CH=CHH), 3.12 (1H, m, P–CHH–P), 2.23 (1H, m, P–CHH–P), 2.02 (m, –CH=CHH and overlapped PMe), 1.93 (15H, d, J = 2 Hz, Cp*), 1.78 (15H, d, J = 3 Hz, Cp*), 1.67 (3H, d, J = 10 Hz, PMe), 1.67 (3H, d, J = 11 Hz, PMe), 1.49 (3H, d, J = 11 Hz, PMe). 13C{1H} NMR(125.65 MHz, CD2Cl2): δ 121.4 (q, J = 320 Hz, CF3), 113.2 (dd, J = 7 Hz, 2 Hz, Ir–C), 94.7 (d, J = 2 Hz, C5Me5), 94.1 (d, J = 3 Hz, C5Me5), 45.7 (d, J = 6 Hz, CH=CH2), 29.1 (d, J = 46 Hz, PMe), 19.9 (d, J = 39 Hz, PMe), 17.6 (dd, J = 36 Hz, 9 Hz, PMe), 16.6 (dd, J = 32 Hz, 11 Hz, PMe), 10.7 (s, C5Me5). 31P{1H} NMR (109.25 MHz, CD2Cl2): δ −34.8 (d, J = 52 Hz), −42.9 (d, J = 52 Hz). Anal calcd for C28H47F3Ir2O3P2S: C, 34.77; H, 4.90. Found: C, 34.47; H, 4.78.

4. Conclusions

We described the successive C–H and C–O bond activation of vinyl ethers by a diphosphine and hydrido-bridged diiridium complex. In the reaction of 2 with 2,3-dihydrofuran, a rapid C–H activation at the 5-position occurred to afford dinuclear oxacarbene complex 3, which was slowly converted into μ-vinylidene complex 4 via the C–O activation mediated by a proton. On the other hand, the reaction of 2 with ethyl vinyl ether resulted in the rapid successive activation of the C–H and C–O bonds to give the μ-vinyl complex 5. It should be noted that the activation of the sp2 C–O bond in vinyl ethers is very rare, and the results shown here provide important information regarding the activation of vinyl ethers by transition metal complexes.

Supplementary Materials

The following are available online at https://0-www-mdpi-com.brum.beds.ac.uk/2304-6740/7/10/121/s1, results of X-ray diffraction studies of the complexes 3–5; the cif and checkcif output files for 3–5.

Author Contributions

Y.T. performed the experiments, analyzed the results, and wrote the draft of the manuscript. T.S. supported the writing of the manuscript. K.-i.F. guided the research, designed the experiments, and wrote the manuscript.

Funding

This work was financially supported by JSPS KAKENHI Grant Number 17750052 and 14750666.

Conflicts of Interest

The authors declare no conflict of interest.

References and Notes

  1. Braun, M. α-Heteroatom-Substituted 1-Alkenyllithium Reagents: Carbanions and Carbenoids for C–C Bond Formation. Angew. Chem. Int. Ed. 1998, 37, 430–451. [Google Scholar] [CrossRef]
  2. Friesen, R.W. Generation and Reactivity of α-Metalated Vinyl Ethers. J. Chem. Soc. Parkin Trans. 1 2001, 1969–2001. [Google Scholar] [CrossRef]
  3. Barluenga, J.; Rodríguez, F.; Álvarez-Rodorigo, L.; Fañanás, F.J. Coupling Reactions of Zirconocene Complexes and Heterosubstituted Alkenes. Chem. Soc. Rev. 2005, 34, 762–768. [Google Scholar] [CrossRef] [PubMed]
  4. Tokunaga, M.; Aoyama, H.; Kiyosu, J.; Shirogane, Y.; Iwasawa, T.; Obora, Y.; Tsuji, Y. Metal Complexes-Catalyzed Hydrolysis and Alcoholysis of Organic Substrates and Their Application to Kinetic Resolution. J. Organomet. Chem. 2007, 692, 472–480. [Google Scholar] [CrossRef]
  5. Png, Z.M.; Zeng, H.; Ye, Q.; Xu, J. Inverse-Electron-Demand Diels-Alder Reactions: Principles and Applications. Chem. Asian J. 2017, 12, 2142–2159. [Google Scholar] [CrossRef]
  6. Ozawa, F.; Kubo, A.; Hayashi, T. Catalytic Asymmetric Arylation of 2,3-Dihydrofuran with Aryl Triflates. J. Am. Chem. Soc. 1991, 113, 1417–1419. [Google Scholar] [CrossRef]
  7. Wu, W.-Q.; Peng, Q.; Dong, D.-X.; Hou, X.-L.; Wu, Y.-D. A Dramatic Switch of Enantioselectivity in Asymmetric Heck Reaction by Benzylic Substituents of Ligands. J. Am. Chem. Soc. 2008, 130, 9717–9725. [Google Scholar] [CrossRef]
  8. Gøgsig, T.M.; Kleimark, J.; Lill, S.O.N.; Korsager, S.; Lindhardt, A.T.; Norrby, P.-O.; Skrydstrup, T. Mild and Efficient Nickel-Catalyzed Heck Reactions with Electron-Rich Olefins. J. Am. Chem. Soc. 2012, 134, 443–452. [Google Scholar] [CrossRef]
  9. Wu, C.; Zhou, J.S. Asymmetric Intermolecular Heck Reaction of Aryl Halides. J. Am. Chem. Soc. 2014, 136, 650–652. [Google Scholar] [CrossRef]
  10. Kazankova, M.A.; Shulyupin, M.O.; Beletskaya, I.P. Catalytic Hydrophosphination of Alkenylalkyl Ethers. Synlett 2003, 2155–2158. [Google Scholar] [CrossRef]
  11. Pahadi, N.K.; Tunge, J.A. Catalytic Intermolecular Hydroamination of Vinyl Ethers. Synlett 2009, 3135–3138. [Google Scholar] [CrossRef] [PubMed]
  12. Ebe, Y.; Nishimura, T. Iridium-Catalyzed Branch-Selective Hydroarylation of Vinyl Ethers via C–H Bond Activation. J. Am. Chem. Soc. 2015, 137, 5899–5902. [Google Scholar] [CrossRef] [PubMed]
  13. Hatano, M.; Ebe, Y.; Nishimura, T.; Yorimitsu, H. Asymmetric Alkylation of N-Sulfonylbenzamides with Vinyl Ethers via C–H Bond Activation Catalyzed by Hydroxoiridium/Chiral Diene Complexes. J. Am. Chem. Soc. 2016, 138, 4010–4013. [Google Scholar] [CrossRef] [PubMed]
  14. Evans, M.A.; Morken, J.P. Stereoselective Synthesis of Furans by the Pd-Catalyzed Oshima–Utimoto Reaction. Org. Lett. 2005, 7, 3367–3370. [Google Scholar] [CrossRef]
  15. Deng, L.; Giessert, A.J.; Gerlitz, O.O.; Dai, X.; Diver, S.T.; Davies, H.M.L. Metal Carbene-Promoted Sequential Transformations for the Enantioselective Synthesis of Highly Functionalized Cycloheptadienes. J. Am. Chem. Soc. 2005, 127, 1342–1343. [Google Scholar] [CrossRef] [PubMed]
  16. Ishida, K.; Kusama, H.; Iwasawa, N. Enantioselective Preparation of 8-Oxabicyclo [3.2.1]octane Derivatives via Asymmetric [3+2]-Cycloaddition of Platinum-Containing Carbonyl Ylides with Vinyl Ethers. J. Am. Chem. Soc. 2010, 132, 8842–8843. [Google Scholar] [CrossRef]
  17. Sherry, B.D.; Toste, F.D. Gold(I)-Catalyzed Propargyl Claisen Rearrangement. J. Am. Chem. Soc. 2004, 126, 15978–15979. [Google Scholar] [CrossRef] [Green Version]
  18. Sherry, B.D.; Maus, L.; Laforteza, B.N.; Toste, F.D. Gold(I)-Catalyzed Synthesis of Dihydropyrans. J. Am. Chem. Soc. 2006, 128, 8132–8133. [Google Scholar] [CrossRef]
  19. Geherty, M.E.; Dura, R.D.; Nelson, S.G. Catalytic Asymmetric Claisen Rearrangement of Unactivated Allyl Vinyl Ethers. J. Am. Chem. Soc. 2010, 132, 11875–11877. [Google Scholar] [CrossRef]
  20. Aoyama, H.; Tokunaga, M.; Hiraiwa, S.-I.; Shirogane, Y.; Obora, Y.; Tsuji, Y. Hydrolysis of Alkenyl Esters and Ethers Catalyzed by Metal Complexes. Org. Lett. 2004, 6, 509–512. [Google Scholar] [CrossRef]
  21. Itoh, H.; Yamamoto, E.; Masaoka, S.; Sakai, K.; Tokunaga, M. Kinetic Resolution of P-Chirogenic Compounds by Palladium-Catalyzed Alcoholysis of Vinyl Ethers. Adv. Synth. Catal. 2009, 351, 1796–1800. [Google Scholar] [CrossRef]
  22. Luo, S.; Vela, J.; Lief, G.R.; Jordan, R.F. Copolymerization of Ethylene and Alkyl Vinyl Ethers by a (Phosphine-Sulfonate)PdMe Catalyst. J. Am. Chem. Soc. 2007, 129, 8946–8947. [Google Scholar] [CrossRef] [PubMed]
  23. Chen, C.; Luo, S.; Jordan, R.F. Cationic Polymerization and Insertion Chemistry in the Reactions of Vinyl Ethers with (α-Diimine)PdMe+ Species. J. Am. Chem. Soc. 2010, 132, 5273–5284. [Google Scholar] [CrossRef] [PubMed]
  24. Carrow, B.P.; Nozaki, K. Synthesis of Functional Polyolefins Using Cationic Bisphosphine Monoxide–Palladium Complexes. J. Am. Chem. Soc. 2012, 134, 8802–8805. [Google Scholar] [CrossRef]
  25. Davies, H.M.L.; Ren, P. Catalytic Asymmetric C–H Activation of Silyl Enol Ethers as an Equivalent of an Asymmetric Michael Reaction. J. Am. Chem. Soc. 2001, 123, 2070–2071. [Google Scholar] [CrossRef]
  26. Kikuchi, T.; Takagi, J.; Ishiyama, T.; Miyaura, N. Iridium-catalyzed Vinylic C–H Borylation of Cyclic Vinyl Ethers by Bis(pinacolato)diboron. Chem. Lett. 2008, 37, 664–665. [Google Scholar] [CrossRef]
  27. Kikuchi, T.; Takagi, J.; Isou, H.; Ishiyama, T.; Miyaura, N. Vinylic C–H Borylation of Cyclic Vinyl Ethers with Bis(pinacolato)diboron Catalyzed by an Iridium(I)-dtbpy Complex. Chem. Asian J. 2008, 3, 2082–2090. [Google Scholar] [CrossRef]
  28. Pawar, G.G.; Singh, G.; Tiwari, V.K.; Kapur, M. Dehydrogenative Heck Reaction (Fujiwara–Moritani Reaction) of Unactivated Olefins with Simple Dihydropyrans under Aprotic Conditions. Adv. Synth. Catal. 2013, 355, 2185–2190. [Google Scholar] [CrossRef]
  29. Wenkert, E.; Michelotti, E.L.; Swindell, C.S.; Tingoli, M. Transformation of Carbon–Oxygen into Carbon–Carbon Bonds Mediated by Low-Valent Nickel Species. J. Org. Chem. 1984, 49, 4894–4899. [Google Scholar] [CrossRef]
  30. Cornella, J.; Martin, R. Ni-Catalyzed Stereoselective Arylation of Inert C–O bonds at Low Temperatures. Org. Lett. 2013, 15, 6298–6301. [Google Scholar] [CrossRef]
  31. Shilov, A.E.; Shul’pin, G.B. Activation of C–H Bonds by Metal Complexes. Chem. Rev. 1997, 97, 2879–2932. [Google Scholar] [CrossRef] [PubMed]
  32. Labinger, J.A.; Bercaw, J.E. Understanding and Exploiting C–H Bond Activation. Nature 2002, 417, 507–514. [Google Scholar] [CrossRef] [PubMed]
  33. Jones, W.D. Advances in Carbon–Hydrogen Activation. In Comprehensive Organometallic Chemistry III: From Fundamentals to Applications; Crabtree, R.H., Mingos, D.M.P., Eds.; Elsevier Ltd.: Oxford, UK, 2007; Chapter 1.25; pp. 699–723. [Google Scholar] [CrossRef]
  34. Fernández-Alvarez, F.J.; Iglesias, M.; Oro, L.A.; Passarelli, V. Bond Activation and Catalysis. In Comprehensive Inorganic Chemistry II; Reedijk, J., Poeppelmeier, K., Eds.; Elsevier Ltd.: Oxford, UK, 2013; Chapter 8.9; pp. 399–432. [Google Scholar] [CrossRef]
  35. Hartwig, J.F. Evolution of C–H Bond Functionalization from Methane to Methodology. J. Am. Chem. Soc. 2016, 138, 2–24. [Google Scholar] [CrossRef]
  36. Milstein, D. Challenging Metal-Based Transformations. From Single-Bond Activation to Catalysis and Metallaquinonoids. Pure Appl. Chem. 2003, 75, 445–460. [Google Scholar] [CrossRef]
  37. Oh, M.; Yu, K.; Li, H.; Watson, E.J.; Carpenter, G.B.; Sweigart, D.A. The Remote Activation of Chemical Bonds via Metal Coordination. Adv. Synth. Catal. 2003, 345, 1053–1060. [Google Scholar] [CrossRef]
  38. Komiya, S.; Hirano, M. Bond Activation by Low Valent Ruthenium Complexes. Dalton Trans. 2003, 1439–1453. [Google Scholar] [CrossRef]
  39. Yu, D.-G.; Li, B.-J.; Shi, Z.-J. Exploration of New C–O Electrophiles in Cross-Coupling Reactions. Acc. Chem. Res. 2010, 43, 1486–1495. [Google Scholar] [CrossRef]
  40. Cornella, J.; Zarate, C.; Martin, R. Metal-catalyzed activation of ethers via C–O bond cleavage: A new strategy for molecular diversity. Chem. Soc. Rev. 2014, 43, 8081–8097. [Google Scholar] [CrossRef]
  41. Tobisu, M.; Chatani, N. Cross-Couplings Using Aryl Ethers via C–O Bond Activation Enabled by Nickel Catalysts. Acc. Chem. Res. 2015, 48, 1717–1726. [Google Scholar] [CrossRef]
  42. Komiya, S.; Srivastava, R.S.; Yamamoto, A.; Yamamoto, T. Selective Cleavage of C–O and/or Si–O Bonds in Trimethylsilyl Ethers Promoted by Cobalt(I), Rhodium(I), and Ruthenium(II) Hydride Complexes. Organometallics 1985, 4, 1504–1508. [Google Scholar] [CrossRef]
  43. Deelman, B.-J.; Booij, M.; Meetsma, A.; Teuben, J.H.; Kooijman, H.; Spek, A.L. Activation of Ethers and Sulfides by Organolanthanide Hydrides. Molecular Structures of (Cp*2Y)2(μ-OCH2CH2O)(THF)2 and (Cp*2Ce)2(μ-O)(THF)2. Organometallics 1995, 14, 2306–2317. [Google Scholar] [CrossRef]
  44. Takaki, K.; Maruo, M.; Kamata, T.; Makioka, Y.; Fujiwara, Y. Selective C–O Bond Cleavage of Vinyl Ethers with Cp*2Sm(thf)n Leading to Vinylsamarium or Enolate Complexes. J. Org. Chem. 1996, 61, 8332–8334. [Google Scholar] [CrossRef] [PubMed]
  45. Bonanno, J.B.; Henry, T.P.; Neithamer, D.R.; Wolczanski, P.T.; Lobkovsky, E.B. Arylamine C–N Bond Oxidative Addition to (silox)3Ta (silox = tBu3SiO). J. Am. Chem. Soc. 1996, 118, 5132–5133. [Google Scholar] [CrossRef]
  46. Planas, J.G.; Marumo, T.; Ichikawa, Y.; Hirano, M.; Komiya, S. Carbon–Oxygen and Carbon–Sulfur Bond Activation of Vinyl Esters, Ethers and Sulfides by Low Valent Ruthenium Complexes. J. Chem. Soc. Dalton Trans. 2000, 2613–2625. [Google Scholar] [CrossRef]
  47. Ferrando, G.; Gérard, H.; Spivak, G.J.; Coalter, J.N., III; Huffman, J.C.; Eisenstein, O.; Caulton, K.G. Facile C(sp2)/OR Bond Cleavage by Ru or Os. Inorg. Chem. 2001, 40, 6610–6621. [Google Scholar] [CrossRef]
  48. Goj, L.A.; Lail, M.; Pittard, K.A.; Riley, K.C.; Gunnoe, T.B.; Petersen, J.L. Reactions of TpRu(CO)(NCMe)(Ph) with Electron-Rich Olefins: Examples of Stoichiometric C–S, C–O and C–H Bond Cleavage. Chem. Commun. 2006, 982–984. [Google Scholar] [CrossRef]
  49. Bradley, C.A.; Veiros, L.F.; Pun, D.; Lobkovsky, E.; Keresztes, I.; Chirik, P.J. Carbon–Oxygen Bond Cleavage with η9,η5-Bis(indenyl)zirconium Sandwich Complexes. J. Am. Chem. Soc. 2006, 128, 16600–16612. [Google Scholar] [CrossRef]
  50. Paneque, M.; Poveda, M.L.; Santos, L.L.; Carmona, E.; Mereiter, K. Generation of Metallacyclic Structures from the Reactions of Vinyl Ethers with a TpMe2IrIII Compound. Organometallics 2008, 27, 6353–6359. [Google Scholar] [CrossRef]
  51. Trovitch, R.J.; Loblovsky, E.; Bouwkamp, M.W.; Chirik, P.J. Carbon–Oxygen Bond Cleavage by Bis(imino)pyridine Iron Compounds: Catalyst Deactivation Pathways and Observation of Acyl C–O Bond Cleavage in Esters. Organometallics 2008, 27, 6264–6278. [Google Scholar] [CrossRef]
  52. Kiyota, S.; Kobori, T.; Soeta, H.; Ichikawa, Y.; Komine, N.; Komiya, S.; Hirano, M. Synthesis of and Catalytic Nitrile Hydration by a Cationic Tris(μ-hydroxo)diruthenium(II) Complex Having PMe3 Ligands. Polyhedron 2016, 120, 3–10. [Google Scholar] [CrossRef]
  53. Shoshani, M.M.; Semeniuchenko, V.; Johnson, S.A. Dismantling of Vinyl Ethers by Pentanuclear [(iPr3P)Ni]5H6: Facile Cooperative C–O, C–C and C–H Activation Pathways. Chem. Eur. J. 2018, 24, 14282–14289. [Google Scholar] [CrossRef] [PubMed]
  54. Halpern, J. Binuclear Oxidative Addition–Reductive Elimination Reactions. Inorg. Chim. Acta 1982, 62, 31–37. [Google Scholar] [CrossRef]
  55. Suzuki, H. Activation of Organic Substrates on Multi-Metallic Sites of Transition Metal Polyhydride Clusters Having C5Me5 Groups as Auxiliary Ligands. Eur. J. Inorg. Chem. 2002, 1009–1023. [Google Scholar] [CrossRef]
  56. Facklar, J.P., Jr. Forty-Five Years of Chemical Discovery Including a Golden Quarter-Century. Inorg. Chem. 2002, 41, 6959–6972. [Google Scholar] [CrossRef]
  57. Powers, I.G.; Uyeda, C. Metal–Metal Bonds in Catalysis. ACS Catal. 2017, 7, 936–958. [Google Scholar] [CrossRef]
  58. Rej, S.; Tsurugi, H.; Mashima, K. Multiply-Bonded Dinuclear Complexes of Early-Transition Metals as Minimum Entities of Metal Cluster Catalysts. Coord. Chem. Rev. 2018, 355, 223–239. [Google Scholar] [CrossRef]
  59. Fujita, K.; Nakaguma, H.; Hamada, T.; Yamaguchi, R. Inter- and Intramolecular Activation of Aromatic C–H Bonds by Diphosphine and Hydrido-Bridged Dinuclear Iridium Complexes. J. Am. Chem. Soc. 2003, 125, 12368–12369. [Google Scholar] [CrossRef]
  60. Takahashi, Y.; Nonogawa, M.; Fujita, K.; Yamaguchi, R. C–H activation on a Diphosphine and Hydrido-Bridged Diiridium Complex: Generation and Detection of an Active IrII–IrII Species [(Cp*Ir)2(μ-dmpm)(μ-H)]+. Dalton Trans. 2008, 3546–3552. [Google Scholar] [CrossRef]
  61. Fujita, K.; Takahashi, Y.; Nakaguma, H.; Hamada, T.; Yamaguchi, R. Activation of C–H and H–H Bonds by Dinuclear Iridium Complexes. Oxidative Addition to Highly Active Unsaturated 32e– Diiridium Species. J. Organomet. Chem. 2008, 693, 3375–3382. [Google Scholar] [CrossRef]
  62. Berry, M.; Howard, J.A.K.; Stone, F.G.A. Chemistry of Di- and Tri-metal Complexes with Bridging Carbene or Carbyne Ligands. Part 2. Formation of Manganese–Platinum, –Palladium, and –Nickel Compounds, and the Crystal Structures of Two Forms of [(OC)4Mn{μ-(1-σ,1—2-η-C=CH–CH2–CH2–O)}Pt(PMe3)2]. J. Chem. Soc. Dalton Trans. 1980, 1601–1608. [Google Scholar] [CrossRef]
  63. Luecke, H.F.; Arndtsen, B.A.; Burger, P.; Bergman, R.G. Synthesis of Fischer Carbene Complexes of Iridium by C–H Bond Activation of Methyl and Cyclic Ethers: Evidence for Reversible α-Hydrogen Migration. J. Am. Chem. Soc. 1996, 118, 2517–2518. [Google Scholar] [CrossRef]
  64. Romero, P.E.; Whited, M.T.; Grubbs, R.H. Multiple C–H Activations of Methyl tert-Butyl Ether at Pincer Iridium Complexes: Synthesis and Thermolysis of Ir(I) Fischer Carbenes. Organometallics 2008, 27, 3422–3429. [Google Scholar] [CrossRef]
  65. Hughes, R.P.; Laritchev, R.B.; Zakharov, L.N.; Rheingold, A.L. Carbon–Fluorine Bond Activation Coupled with Carbon–Carbon Bond Formation at Iridium. Confirmation of Complete Kinetic Diastereoselectivity at the New Carbon Stereocenter by Intramolecular Trapping Using Vinyl as the Migrating Group. J. Am. Chem. Soc. 2005, 127, 6325–6334. [Google Scholar] [CrossRef] [PubMed]
  66. Chin, C.S.; Lee, H.; Park, H.; Kim, M. Synthesis of Cross-Conjugated Olefins from Alkynes: Regioselective C–C Bond Formation between Alkynes. Organometallics 2002, 21, 3889–3896. [Google Scholar] [CrossRef]
  67. Wang, L.-S.; Cowie, M. Cationic Vinylidene-Bridged Complexes and Their Reactions with Alkynes to Yield Either Alkyne- and Vinylidene-Bridged or Bis(vinylidene) Products. Facile Interconversion between Terminal and Bridging Vinylidene Bonding Modes. Organometallics 1995, 14, 3040–3057. [Google Scholar] [CrossRef]
  68. Torkelson, J.R.; McDonald, R.; Cowie, M. C–H Bond Activation and C–C Bond Formation in the Reactions of the Methyl Complex [Ir2(CH3)(CO)2(Ph2PCH2PPh2)2][CF3SO3] with Alkynes. Organometallics 1999, 18, 4134–4146. [Google Scholar] [CrossRef]
  69. McDonald, F.E.; Connolly, C.B.; Gleason, M.M.; Towne, T.B.; Treiber, K.D. A New Synthesis of 2,3-Dihydrofurans: Cycloisomerization of Alkynyl Alcohols to Endocyclic Enol Ethers. J. Org. Chem. 1993, 58, 6952–6953. [Google Scholar] [CrossRef]
  70. Fujita, K.; Nakaguma, H.; Hanasaka, F.; Yamaguchi, R. Synthesis of a DMPM and Hydrido-Bridged Diiridium Complex, [(Cp*Ir)2(μ-dmpm)(μ-H)2][OTf]2, and Its Reactivity toward Alkynes and Isocyanides. Organometallics 2002, 21, 3749–3757. [Google Scholar] [CrossRef]
Inorganics 07 00121 g001 550
Figure 1. Binding modes in the complex 3.
Figure 1. Binding modes in the complex 3.
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Figure 2. ORTEP drawing of the cationic part of 3. Hydrogen atoms are omitted for clarity.
Figure 2. ORTEP drawing of the cationic part of 3. Hydrogen atoms are omitted for clarity.
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Figure 3. ORTEP drawing of the cationic part of 4. Hydrogen atoms are omitted for clarity.
Figure 3. ORTEP drawing of the cationic part of 4. Hydrogen atoms are omitted for clarity.
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Scheme 1. Plausible pathway for the transformation of 3 into 4.
Scheme 1. Plausible pathway for the transformation of 3 into 4.
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Figure 4. ORTEP drawing of the cationic part of 5. Hydrogen atoms are omitted for clarity.
Figure 4. ORTEP drawing of the cationic part of 5. Hydrogen atoms are omitted for clarity.
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Figure 5. Structure of intermediate C.
Figure 5. Structure of intermediate C.
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Takahashi, Y.; Shimbayashi, T.; Fujita, K.-i. Successive Activation of C–H and C–O Bonds of Vinyl Ethers by a Diphosphine and Hydrido-Bridged Diiridium Complex. Inorganics 2019, 7, 121. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics7100121

AMA Style

Takahashi Y, Shimbayashi T, Fujita K-i. Successive Activation of C–H and C–O Bonds of Vinyl Ethers by a Diphosphine and Hydrido-Bridged Diiridium Complex. Inorganics. 2019; 7(10):121. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics7100121

Chicago/Turabian Style

Takahashi, Yoshinori, Takuya Shimbayashi, and Ken-ichi Fujita. 2019. "Successive Activation of C–H and C–O Bonds of Vinyl Ethers by a Diphosphine and Hydrido-Bridged Diiridium Complex" Inorganics 7, no. 10: 121. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics7100121

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